Recently, green tea has received a great deal of attention from people in Thailand due to its health benefits. In Thailand, the majority of green tea is produced in Chiang Rai province which is approximately 84% of the total green tea production in Thailand. The quality of green tea must meet the standards set by the Ministry of public Health considered to be moisture content, total ash, water soluble ash, hot water extract, and caffeine content. However, it is now widely accepted that the determinant of green tea quality is its catechin content, Because of the growing popularity of tea in recent years